"Every successive British Government, Labor or Conservative, looking at the deterrent, has always taken the decision to renew it," he said. "You have to be absolutely sure that no such threat will emerge to the U.K. all the way till 2060, if you're going to be happy to dispense with the nuclear deterrent we have, and I'm not prepared to take that risk."
But the program has proved controversial with some Scottish political figures.
Scottish First Minister Nicola Sturgeon has previously said that the renewal of Trident could trigger a second independence referendum within Scotland, and Salmond's comments about the program's dangers were made during a parliamentary debate into whistleblower allegations of lax security at the Trident naval base in Faslane, within Scotland. The base faced a blockade by anti-nuclear protesters in April.
Does the Iraqi Army lack the will to fight?
The U.K. defense minister also appeared to draw a line under how much support his country might provide to the Iraqi army.
While he expressed support for Iraq's battle against the Islamic State and said the U.K. would continue to provide training, equipment and air support, he added that the ground battle would ultimately have to be won by the Iraqi Army.
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"This is, in the end, a campaign that can only be won by Iraqi boots on the ground, with the support of the local population," he said. "What's important too, is that Iraq continues the reforms that it's planning, that it gets the National Guard legislation through, and where towns and villages are recaptured from ISIL, it's able to hold them securely with the support of the local population, with a security that the Sunnis will accept."
The U.K. has provided some 300 air strikes in support of Iraq - the second largest number within the Coalition. Fallon's comments came as U.S. Secretary of Defense Ashton Carter said in an interview last week that Iraqi forces simply lacked the will to fight.
Playing war games with Russia
Fallon also expressed concern about military tensions with Russia, after the U.K. airforce intercepted Russian aircraft near Britain's airspace in several incidents in recent months.
The Russian military flights were provocative, disruptive and unnecessary, Fallon said and he reiterated that the U.K. would not tolerate incursions into its airspace.
"I think Russia is simply testing NATO. They've been testing not simply our defenses. They've been testing Norwegian defenses, they've been testing Scandinavian countries and the Baltics," he said. "They've been probing I think, NATO's general resilience, and we've responded to that, not simply by using our quick reaction Typhoons and getting them up there as quickly as possible, but also, by contributing to the Baltic Air Policing Mission."
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At the same time, Fallon expressed concern about Russia's compliance with the Minsk Protocol, a planned Ukraine cease fire that was signed last year.
German Chancellor Angela Merkel and French President Francois Hollande have both called on Russia to implement the plan, and Minister Fallon confirmed to CNBC that Russia has been amassing heavy artillery along the border of Eastern Ukraine in breach of the agreement.
"We want to see the Minsk Agreement fully implemented, and obviously, we're working hard with our partners to ensure that the sanctions are rolled over until those agreements are fully implemented," he said.